If Iran wants nuclear energy, then why not give them the same offer we gave North Korea and actually do what we say this time? We offered to build North Korea light water reactors from which fissile material cannot be harvested. If Iran doesn't trust us to build it then get the Russians or French to build them. Doing this would call Iran's bluff on their entire nuclear processing program and portray the US (and other western nations that might help broker the deal) as willing to assist Iran with its problems. If Iran balks, then the world would plainly see that nuclear weapons really are Iran's goal and nobody wants an Iran with nuclear weapons.
As a theoretical scernario that works fine, but when or if Tehran's bluff is called - and let's be under no illusions about the fair certainty that it already has been - (behind closed doors) then it would put even more, perhaps irresistable pressure on the West (and/or Russia and China) to act (militarily) as a result. I doubt anybody wants that either, and I include the Israel in that.
Until then, the US (et al) can berate Tehran, Israel can posture. But in the absence of
proof, none would have carte blanche to take any actual action because it would be based on a public perception that Iran's persuit of weapons is merely an
allegation (does that sound familiar?). I doubt that's a desirable outcome either.
But talk, and sanctions while ineffective at least provide the masses with the illustion of doing ... something while
actually doing nothing, playing the waiting game in the hope that things may change. It may be a vain hope but it's cheap and 'comparatively' risk free.
In that sense, Iran has 'us' right where it wants 'us'.